''Pterostylis xerophila'', commonly known as the desert greenhood, is a plant in the orchid family Orchidaceae and is endemic to South Australia. Both flowering and non-flowering plants have a relatively large rosette of leaves. Flowering plants also have up to eight translucent white, green and reddish-brown flowers with an insect-like labellum.

Description

''Pterostylis xerophila'' is a terrestrial, perennial, deciduous,

herb In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal ...

with an underground tuber and a rosette of between three and ten leaves. The leaves are long and wide. Flowering plants have a rosette at the base of the flowering stem but the leaves are usually withered by flowering time. Up to eight white, green and reddish-brown flowers long and wide are borne on a flowering stem tall. The dorsal sepal and

petal Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...

s form a hood or "galea" over the column with the dorsal sepal having a narrow, upturned tip long. The lateral sepals turn downwards, are wider than the galea, dished, and suddenly taper to narrow tips long. The labellum is insect-like, about long, wide with a thin "body" and a thickened "head" end. Each side of the labellum has four to six forward-pointing bristles up to long. Flowering occurs from September to November.

Taxonomy and naming

''Pterostylis xerophila'' was first formally described in 1986 by Mark Clements from a specimen grown in Adelaide from material collected in the Great Victoria Desert. The description was published in the fourth edition of the ''Flora of South Australia''. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

(''xerophila'') is derived from the Ancient Greek words ''ξερός (xeros)'', meaning “dry” and ''φίλος (phílos)'', meaning "dear one" or "friend". Its common name as listed on the Commonwealth's SPRAT database is desert greenhood.

Distribution and habitat

The desert greenhood usually grows in granite or quartzite rock outcrops in areas receiving an average annual rainfall of less than , in and near the Great Victoria Desert.

Conservation

''Pterostylis xerophila'' is classified as "vulnerable" under the Australian Government '' Environment Protection and Biodiversity Conservation Act 1999'' and the South Australian Government '' National Parks and Wildlife Act 1972''. Little is known about the threats to this greenhood but include grazing by feral rabbits and goats, weed invasion, accidental destruction by vehicle movement and inappropriate fire regimes.

References

{{Taxonbar, from=Q15492054 xerophila Endemic orchids of Australia Orchids of South Australia Plants described in 1986